A device that detects the SOx concentration in exhaust gas from an internal combustion engine using a gas sensor that includes a catalyst that captures S components in the exhaust gas when the exhaust gas air-fuel ratio is lean and releases the captured S components when the exhaust gas air-fuel ratio is stoichiometric or rich, and a temperature measurement device that measures the temperature of the catalyst has already been disclosed in Patent Literature 1, for example.
A limiting current-type sensor is disclosed in Patent Literature 2 and 3. The sensor includes a solid electrolyte that has oxide ion conductivity and a pair of electrodes that are provided on opposite sides of the solid electrolyte, and detects the O2 concentration in exhaust gas based on a limiting current that is generated when a predetermined voltage is applied between the pair of electrodes. In addition, it is disclosed in Patent Literature 2 that the sensor is deteriorated when S components in the exhaust gas are adsorbed on the sensor electrodes.